PARAMETERISATIONS OF WET DEPOSITION

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PARAMETERISATIONS OFWET DEPOSITION

• Ernst Meijer
• AC3 Meeting
• 7-8 November
• De Bilt, Netherlands

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AC3.2.1 Precipitation impact on sulphur and
nitrogen compounds

• KNMI will test different wet removal
  parameterisations
• KNMI will provide distributions of wet removal
  parameters
• CNRS-LSCE and UCAM-DCHEM will use these
  distributions
• Report
• Milestones
• month 12 description
• month 12 KNMI provides distributions of wet
  removal parameters
• month 14 simulations (KNMI only?)
• month 18 report

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Proposed description

• All provide brief descriptions of their wet
  removal scheme (convective and large-scale) with
  parameter requirements
• Do not implement completely new schemes
• Improve current KNMI scheme using new/other ECMWF
  archived fields, e.g.
• 3-D precipitation fields
• overcast cloud cover for below scavenging)
• ....
• Investigate effect of spin-up time for HNO3
  distribution
• Investigate effect of on-line / off-line
  convection

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Convective wet removal ERA40 or operational?

• off-line calculation of convective mass-fluxes
• archived convective precipitation
• ? poor correlation between convective
  precipitation and other convective parameters

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Proceed with ERA-40 convective fields

• Problems with too fast circulation in ERA-40!
• Therefore
• Investigate possibility to combine operational
  data from ECMWF with ERA-40 convective fields
• Impact studies, using only
• only OD
• only ERA-40
• combination of ERA-40 convection with OD
• Also
• Evaluate archived convection fields from
  operational data for 1 month (April 2003).

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Model simulations

• KNMI will provide detailed requirements in month
  12
• KNMI will provide the necessary fields
• Spin-up time (1 year)
• 1 year (2003)
• coarse and high resolution?

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Comparison with observations

• Include removal rate of HNO3 in list of output
  diagnostics for WP3.1 (other diagnostics?)
• point-to-point comparison
• curtain plots
• monthly means
• Select campaign data for case analysis

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Output diagnostics

• Monthly mean distributions of NOy and HNO3
• Monthly mean distributions of SO4
• Monthly mean distributions of wet removal of HNO3
  (nmol/mol/month)